You place six jars (left to right: coffee, arsenic, and sugar on the top shelf; snuff, tea, and salt on the bottom shelf) and have somebody else fill them up with these ingredients, making sure each jar contains something other than what the label says.

You are told that the salt is located under the jar containing snuff, and that the sugar is located directly to the right of the jar containing coffee.

Where is the arsenic?

The coffee-sugar pair can't be on the top left as that would put the coffee in the jar labeled coffee, and not on the top right as that would put the sugar in the jar labeled sugar, so the coffee-sugar pair is on the bottom.

If the coffee-sugar pair were on the bottom left, the salt would have to be on the bottom right, but that jar is labeled salt, so the coffee-sugar pair must be on the bottom right, with the snuff-over-salt pair on the top and bottom left.

The arsenic can't go on the top-middle, so it must be on the only remaining spot: the top-right, in the jar labeled sugar.

Posted by Charlie on 2008-08-10 16:37:35